It takes very little mass in the form of small grains in a circumstellar environment to produce substantial scattered light and thermal infrared emission. The surface brightness of the solar system's zodiacal cloud, with a total mass equal only to that of a single small asteroid, would make it difficult to detect Earth directly from neighboring stars at both optical and IR wavelengths.
On the other hand, the presence of small dust grains with lifetimes much shorter than the age of the solar system would instantly indicate to an external observer that at least planetesimal-sized bodies exist in our system as reservoirs for the dust material. And if planetesimals, then why not planets? Furthermore, large masses embedded in the dust make their presence known through their gravitational effects on the cloud's morphology.
Thus, a planetary system's dust can both obscure and indicate the presence of planets. This report will attempt to summarize the current state of knowledge about our solar system's dust component, relate it to dust discovered around some nearby main sequence stars, and compare methods for detecting and characterizing extrasolar zodiacal clouds on the road to finding extrasolar earth-like planets.
Last updated March-06-1998